Bacteria-mediated synthesis of silver nanoparticles under photo-irradiation and their efficacy against methicillin-resistant Staphylococcus aureus

Abstract

ABSTRACT Over the last few decades, morbidity and mortality rates from infectious diseases have increased due to antibiotic resistance. Community-acquired and nosocomial-related methicillin-resistant bacterial strains are proliferating, which makes the discovery of new antibiotics and the search for new approaches to fight pathogenic bacteria an urgent task. One of the new promising classes of antimicrobials is silver nanoparticles (AgNPs). The goal of this study was to investigate the bacteria-mediated synthesis of AgNPs and evaluate their antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). Indigenous bacteria from soil samples from Multan (Pakistan) were isolated and three strains – Klebsiella spp., Citrobacter freundii, and Bacillus cereus – were selected for the synthesis of AgNPs under photo-irradiation. The biosynthesis of AgNPs was confirmed by UV-visible spectroscopy. The AgNPs obtained in our experiments showed strong antibacterial activity against MRSA isolated from patients with community-acquired skin infections (from the dermatology ward of Jinnah Hospital Lahore) with 15 mm to 25 mm zones of inhibition (ZOI) according to the well diffusion method. The results of this project showed that microbial reduction of AgNO3 under photo-irradiation produces AgNPs that are highly active against MRSA.